Carbonate salts solubility

Lead Carbonate. Lead carbonate [598-63-0] PbCO, mol wt 267.22, d = 6.6g/cm, forms colorless orthorhombic crystals it decomposes at about 315°C. It is nearly insoluble in cold water (0.00011 g/100 mL at 20°C), but is transformed in hot water to the basic carbonate, 2PbC03 Pb(OH)2. Lead carbonate is soluble in acids and alkalies, but insoluble in alcohol and ammonia. It is prepared by passing CO2 iuto a cold dilute solution of lead acetate, or by shaking a suspension of a lead salt less soluble than the carbonate with ammonium carbonate at a low temperature to avoid formation of basic lead carbonate. 

Almost all the Earth s carbon is found in the lithosphere as carbonate sediments that have precipitated from the oceans. Shells of aquatic animals also contribute CaC03 to the lithosphere. Carbon returns to the hydrosphere as carbonate minerals dissolve in water percolating through the Earth s crust. This process is limited by the solubility products for carbonate salts, so lithospheric carbonates represent a relatively inaccessible storehouse of carbon. 

The feasibility of the above reaction ensues from the data on the solubility products of lead sulfate and lead carbonate salts. Evidence abounds that both sulfate and carbonate ions are present. 

If S moles of CaCC>3 dissolve in a liter of water, then S moles each of calcium ion and carbonate ion form. With these ion concentrations equal to S, the solubility of CaCC>3 is calculated as 9.3 x 10 5 M. The higher solubility of magnesium carbonate in water, 6.3 x 10 3 M, results from the larger solubility product constant. Nevertheless, both of these carbonate salts are rather insoluble, and the excess carbonate anions provided by the sodium carbonate effectively precipitate the calcium and magnesium ions from solution. 

The basicity of the molten carbonate is defined as equal to -log (activity of O ) or -log aM20, where a is the activity of the alkali metal oxide M2O. Based on this definition, acidic oxides are associated with carbonates (e g., K2CO3) that do not dissociate to M2O, and basic oxides are formed with highly dissociated carbonate salts (e.g., U2CO3). The solubility of NiO in binary carbonate melts shows a clear dependence on the acidity/basicity of the melt (18,19). In relatively acidic melts, NiO dissolution can be expressed by... 

The physical and chemical properties of elemental thorium and a few representative water soluble and insoluble thorium compounds are presented in Table 3-2. Water soluble thorium compounds include the chloride, fluoride, nitrate, and sulfate salts (Weast 1983). These compounds dissolve fairly readily in water. Soluble thorium compounds, as a class, have greater bioavailability than the insoluble thorium compounds. Water insoluble thorium compounds include the dioxide, carbonate, hydroxide, oxalate, and phosphate salts. Thorium carbonate is soluble in concentrated sodium carbonate (Weast 1983). Thorium metal and several of its compounds are commercially available. No general specifications for commercially prepared thorium metal or compounds have been established. Manufacturers prepare thorium products according to contractual specifications (Hedrick 1985). 

According to the ionic hypothesis, if the solubility product [Li]2[C0"3] is not altered, the solubility can be increased by the union of one or other of the ions of the carbonate forming complexes with the added salt. This effect is not very marked with potassium or sodium chloride or nitrate. The marked increase in the solubility with sodium and potassium sulphates is due to the formation of lithium sulphate, but with the ammonium salts soluble complexes like Li(NH3) and NH2C00 may be formed just as is the case with magnesium carbonate in the presence of ammonium salts. 

The elements have remarkably low specific gravity, and a high atomic volume (q.v.). The oxides and hydroxides are markedly basic they do not exhibit acidic qualities. The physical properties of the salts—solubility in water, molecular volume, optical properties, and the variation in the form of the crystals show the same order of variation as the atomic weights of the elements. Lithium differs in mafiy respects from the other members of the family. The salts of the alkali metals —nitrates, chlorides, sulphides, sulphates, phosphates, carbonates, etc.—are nearly all soluble in water, although lithium, carbonate, phosphate, and fluoride are very... 

Salt Effect on Carbon Dioxide Solubility in Mixture of Methanol and Water... 

The variations of carbon dioxide solubilities with salt concentrations are shown in Figures 1 and 2 as forms of the modified Setschenow plot for each solvent... 

Strontium, Barium Strontium was discovered near, and named after, the small town of Strontian, Scotland, in 1787. There are no commercial uses for the pure metal, but the carbonate salt, SrC03, is used in the manufacture of glass for color TV picture tubes. Barium is found principally in the minerals witherite (BaC03) and barite (BaSC ), after which it is named. Though water-soluble salts of barium are extremely toxic, barium sulfate is so insoluble that it is used in medicine as a contrast medium for stomach and intestinal X rays. Like strontium, barium metal has no commercial uses, but various compounds are used in glass manufacture and in drilling oil wells. 

The second reaction is the partial addition of lime to convert only the temporary hardness salt, calcium bicarbonate, to the carbonate salt. Typically, approximately 15 to 20 ppm of the calcium carbonate will remain in solution, while the remainder will precipitate as an insoluble salt. If full softening of other temporary hardness bicarbonate salts is required (those of magnesium, sodium, etc.), the application of further amounts of lime converts these to soluble carbonates. 

A benzene solution of 2.2 parts of a-chloro-y-quinoline-carboxylic acid chloride is gradually mixed, while cooling, with 2.3 parts of unsymmetrical diethylethylenediamine. When the reaction is at an end the solution is washed with water and the new base extracted by means of hydrochloric acid. The base is precipitated by means of sodium carbonate and extracted with benzene. The solvent is distilled and the base recrystallized from petroleum ether. The a-chloro-y-quinoline-carboxylic acid diethyl-amino-ethylene amide forms colorless lamina crystals of melting point 74°C. With acids the base forms neutral salts soluble in water. 

Strontium sulphate would dissolve in the solution of sodium carbonate in the same manner as it would in pure water until it had saturated the solution, and its solubility product, which is equal to 0.0006 X 0.0006, was reached, but for the fact that long before this could occur the solution would be supersaturated with respect to strontium carbonate, the solubility product of which is only equal to 0.00007 X 0.00007. Thus strontium carbonate is precipitated continuously as strontium sulphate dissolves and since the solution cannot become saturated with the latter as long as a large excess of carbonate ions is present, the solid salt finally remaining will consist entirely of strontium carbonate, provided a sufficient amount of sodium carbonate were employed. The reaction which takes place is, however, reversible, SrSO + Na2C03 SrCOj + NasSO, and, if strontium carbonate were boiled with a solution of sodium sulphate, the solid would change into sulphate until carbonate ions had accumulated in the solution to such an extent as to make the concentration ratio [C03 ] [SO4 ] = 1 74. When this ratio prevails, both solids are in equilibrium with the solution and no change takes place in either direction. 

Effervescents comprise a soluble organic acid and an alkali metal carbonate salt. Citric acid is most commonly used for its flavor-enhancing properties. Malic acid imparts a smoother after taste and fumaric, ascorbic, adipic, and tartaric acids are less commonly used [14], Sodium bicarbonate is the most common alkali, but potassium bicarbonate can be used if sodium levels are a potential issue with the formulation. Both sodium and potassium carbonate can also be employed. Other excipients include water-soluble binders such as dextrose or lactose, and binder levels are kept to a minimum to avoid retardation of disintegration. All ingredients must be anhydrous to prevent the components within the formulation reacting with each other during storage. 

Table I. Experimental Results of Carbon Dioxide Solubility in Aqueous Binary Mixed-Salt Solutions at 25°C and 1 atm...

Ferrous carbonate, FeCOg, occurs in nature as a mineral, and can be obtained as a white precipitate by the action of carbonate ion on ferrous ion in the absence of dissolved oxygen. Like calcium carbonate, ferrous carbonate is soluble in acidic waters, the bicarbonate, Fe(HC03)2, being a soluble salt. Hard waters often contain ferrous or ferric ion. 

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